Free piston injection engine



FREE PISTON INJECTION ENGINE Filed Oct. 15, 1958 3 Sheets-Sheet 1 INVENTOR. Andrew J.Sobol' ATTORNEYS Oct. 25, 1960 A. J. SABOL FREE PISTON INJECTION ENGINE 3 Sheets-Sheet 2 Filed Oct. 15, 1958 INVENTOR. Andrew J. Sobol $94M ATTORNEY$ Oct. 25, 1960 A. J. SABOL FREE! PISTON INJECTION ENGINE 3 Sheets-Sheet 3 Filed Oct. .15, 1958 ISu mvamon. Andrew J. Subol Y 1 B a; g ;7/

%I A TTORNEYS United States FREE PISTON INJECTION ENGINE Andrew J. Sabol, McKees Rocks, Pa. (214 Munson Ave, Pittsburgh, Pa.)

Filed Get. 15, 1958, Ser. No. 767,393

6 Claims. ((11. 60-13) This invention relates to engines and particularly to a free piston engine in which the reciprocatory movement of pistons is translated into rotary motion without crankshafts or pivotal piston rods.

Conventional internal combustion engines are provided with crankshafts and pivoted connecting rods whereby the reciprocatory motion of the pistons is translated to rotary motion. Such mechanisms are well known to have serious problems of wear on the many bearing surfaces as well as inertia problems in starting and in rapid acceleration. In an effort to overcome these problems of conventional internal combustion engines it has been proposed to use so-called free piston engines in which two opposed pistons move on a common axis and the exhaust gases are removed and used to drive a power turbine. These free-piston engines have required a delivery system for hot gases to a remote turbine, a surge tank to even out pulsations and considerable expensive tubing and piping.

I have invented an engine of the free-piston type which overcomes the difiiculties of ordinary internal combustion of the crankshaft type and at the same time eliminates the surge tanks, air cushion tanks and complex fluid delivery tubing of the known free piston engines.

I provide preferably a pair of spaced cylinders on a common axis, a pair of pistons movable in said cylinders and connected for unitary movement, a vaned rotor in each of said cylinders between the two pistons, said rotors connected by a common shaft rotatable around the axis of the cylinders, power transmitting means on said shaft, means introducing a combustible mixture into each cylinder between the cylinder and the piston therein and activated by movement of the piston, connections between the cylinders delivering the exhaust gas formed by combustion of the combustible material from the area between a cylinder and its piston to the area between a vaned rotor and its adjacent piston whereby movement of the piston forces the exhaust gases through the vanes of the rotor, a passageway surrounding the cylinder, an auxiliary rotor moving in said passageway to deliver atmospheric air thereto and openings between said passageway and the cylinder adapted to deliver air under pressure alternatively into the area between the piston and the rotor and into the cylinder between the cylinder and the piston immediately following each exhaust stroke of the piston. Preferably, the pistons are connected together by a rod operating axially of the cylinders and surrounded by the hollow shaft connecting the vaned rotors. In a preferred embodiment the power transmitting means on the hollow shaft is a pinion [gear or the like.

In the foregoing general description, I have set out certain purposes, objects and advantages of this invention. Other objects, purposes, and advantages will be apparent from a consideration of the following detailed description of a preferred embodiment and the accompanying drawings in which,

2,957,305 Patented Oct. 25, 1960 ice Figure 1 is a longitudinal section of a preferred form of engine according to my invention;

Figure 2 is a section on the line II-II of Figure 1;

Figure 3 is a section on the line III-III of Figure 1; and

Figures 4A-C are longitudinal generally schematic sectional views of the engine of Figure 1 showing the pistons in various operative positions.

Referring to the drawings, I have illustrated a pair of hollow cylinders 10 and 11 spaced apart on a common axis. Each cylinder is provided with a piston 12 and 13 respectively connected by a shaft 14 on the axis of the cylinders so that when piston 12 is at one end of cylinder 10, piston 13 is at the opposite end of cylinder 11. The pistons 12 and 13 divide each of the cylinders 10 and 11 into an expansible combustion chamber (10a and 11a) and an expansible exhaust chamber (10b and 11b). The opposite ends of the cylinders 10 and 11 are provided with an intermediate Wall 15 carrying fuel injectors 15a in the form of a ring of spaced apart injectors. Each of the pistons 12 and 13 carries an injector ring 16 adapted to strike the injectors 15a when the piston 12 or 13 reaches the end of its respective cylinder 10 or 11 as the case may be. The injector ring 16 striking the injector 15a causes fuel to be injected from fuel lines 17 into the cylinder between the end of the cylinder and the piston. The intermediate walls 15 of cylinders 10 and 11 are connected by a hollow shaft 26 extending axially within shaft 14. The opposite ends of each cylinder 10 and 11 are also provided with an air starting valve 18 through which compressed air may be introduced to start the engine in operation. Each cylinder is provided with a closing wall 19 spaced inwardly from the open end 20 of the cylinder. Each said endwall 19 is provided with ports 21. A vaned rotor 22 is provided for rotation in the open end of the cylinder adjacent the closure member 19. The rotor 22 is provided with vanes 23 in line with ports 21. When one of the pistons 12 or 13 moves in its respective cylinder from a position adjacent the injectors to a position adjacent the closure member 19, gases in the cylinder 10 or 11, as the case may be, behind the piston 12 or 13 are forced through the ports 21 into vanes 23 causing the vaned rotor 22 to rotate. The vaned rotors 22 in the two cylinders are connected by a common hollow shaft 24 surrounding the rod 14 and rotatable with the rotors. A drive gear 25 is fixed on this hollow shaft.

Hot exhaust gases are delivered from the area between the piston and the end of the cylinder through ports 27, into the interior of shaft 26 to like ports 27 in the area between the end closure member 19 and the piston in the opposite cylinder.

Each of the cylinders is surrounded by an outer spaced cylindrical wall 30 forming an annular channel 31 around the cylinder and each of the cylindrical Walls 30 is surrounded by a second cylindrical wall 32 forming a second annular passageway 33 about the cylinder 10 or 11 as the case may be. The annular areas 31 are provided with ports 34 into the wall of the cylinder 1! or 11. The annular areas 31 are closed at the end adjacent the rotor 22 by an annular ring 28. A second rotor 36 is mounted on a stub shaft 36:: fixed to the end of the cylinder opposite rotor 22. Rotor 36 is provided with vanes 37 which open to the atmosphere and force air from rear opening 38 through the annular chamber 31 into cylinders 10 and 11 at all times when the engine is operating. When the piston 12 or 13 has completed its exhaust stroke air is forced into the area between the piston and the cylinder end. When the piston in one cylinder is in its power stroke air is forced into the area between the piston and vaned rotor of the other cylinder, providing additional gas for expansion and reducing the temperature of the 3 exhaust gases passing through the vaned rotor. Rotor 36 is provided with second vanes 37a which communicate with passage 33 to receive and be driven by the hot gases passing through vanes 23 by way of passageways 39 to deliver the gases into exhaust through annular chamber 33.

In operation, compressed .air :is introduced alternately through the valves 18 -into cylinders'10 and 11 behind pistons 12 and 13 causing the pistons to reciprocate. At this time port 34 is closed by valve 35 actuated by-springs 35a. When one of the pistons is forced to the 'end of the cylinder with its injector ring 16 in contact with the injector 15, fuel is injected into the compressed air in the restricted zone and is fired. This forces the-piston to the other end of the cylinder which, in turn, forces the opposite piston into contact with its injectors causing fuel to be injected and fired. When 'the engine has fired and is operating :the compressed air is 'cut off and valves 35 are opened by pressurefrom the .air delivery vanes .37. When piston '12 is fired it passes from the position shown in Figure 4A through the position 4B to the position shown in Figure 4C, the exhaust. gases pass out through port 27 through hollow shaft 26'into cylinder :11 behind'piston 13 where they are mixed with air coming from rotor vanes 37 through port 34. This air'cools the exhaust gas to a certain degree but is itself warmed and expanded. When the gases between piston 13 and'cylinder 11 are fired, the exhaust gases transferred from cylinder and the input air from vanes 37 and port 34 between piston 13 and end member '19 are forced outwardly through ports 21 and vanes 23, thereby causing the rotor 22 to rotate and impart rotation to the drive gear 25. When the piston 13 passes the port 27 on shaft 26, the vane 37 acts as a supercharger to purge the cylinder and deliver air into cylinder 11 for the next compression and firing stroke. The hot' gases going out through port 21 and vane '23 are delivered through passageway 39 to vane 36a where they are forced through the vanes .to exhaust thereby driving the rotor.

It is evident from the foregoing description that the engine of this invention'is much more compact and much more easily constructed than conventional engines and that it eliminates the problems of crankshafts, rotating piston rods "and the lubrication of "such devices. There are fewer manufacturing parts and little vibration. Moreover, any type of fuel, including low grade fuels, may be successfullyused in this engine.

While I have illustrated anddescribed 'a present preferred form of my invention, it will be understood that the invention may be otherwise embodied within the scope of the following claims.

I claim:

1. An engine of the free piston type'compr'ising 'afpair of spaced cylnders on a common axis, a piston movable in each of said cylinders and connected for unitary movement, an expansible combustion chamber on'one side of each piston and an expansible exhaust chamber on the other side of each piston, a vaned rotor adjacent each exhaust chamber, said rotors being connected by a common shaft rotatable around the axis of the cylinders, power transmitting means on said shaft, means introducing a combustible material alternately into the combustion chamber of each cylinder, connections between the cylinders delivering exhaust gases formed by combustion of the combustible material from said combustion chamber of one cylinder to the exhaust chamber of the other cylinder whereby movement of the piston in said other cylinder forces the exhaust gas through the vanes of said rotor, a passageway surrounding each cylinder, an auxiliary rotor moving in each said passage'delivering air thereto and openings between each said passageway and its cylinder delivering air under pressure alternately into the exhaust chamber of each cylinder during the power stroke in the other cylinder and into the combustion chamber of each cylinder following the power stroke in that cylinder 4 and the rotor and into the cylinder between the cylinder and piston following each exhaust stroke of the piston.

2. An engine of the free piston type comprising a pair of spaced cylinders on a common axis, a piston movable in each of said cylinders and connected for unitary movement, an expansible combustion chamber on one side of each piston and an expansible exhaust chamber on the other side of each piston, a varied rotor adjacent each exhaust chamber, said rotors being connected by a common shaft rotatable around the axis of the cylinders, power transmitting means on said shaft, means introducing a combustible material alternately into the combustion chamber of each cylinder, connections between the cylinders delivering exhaust gas formed by combustion of the combustible material from said combustion chamber of one cylinder to the exhaust chamber of the other cylinder whereby movement of the piston in said other cylinder forces the exhaust gas through the vanes of said rotor, a passageway surrounding each cylinder, an. auxiliary rotor moving ineach said passage deliveringair thereto, openings between each said passageway and its cylinder delivering air underpressure alternately into the exhaust chamber in each cylinder during thepowerstroke in the other cylinder and into the combustion chamber of each cylinder following the power stroke in saidcylinder anda drive rotor-connected to'the auxiliaryrotor for'rotation thereof, said drive rotor receiving the exhaust .gas from said vaned rotor and driven thereby.

3. An engine of the free piston type comprising a pair of spaced cylinders on acommon'axis, apiston movable in each of said cylinders and connected for unitary movement, an expansible combustion chamber on one side of each piston and an expansible exhaust chamber on the other side of each piston, a varied driverotor adjacent each exhaust chamber, said rotors being connected by a common shaft rotatable around the axis'of thecylinders, power transmitting means on said shaft, means introducing a combustible material alternately into'the combustion chamber of each cylinder, connections between thecylinders delivering exhaust gas formed by combustion of the combustible material from said combustion chamber of one cylinder to the exhaust chamber of the other cyiinder whereby movement of the piston in said other cylinder forces the exhaust gas through the vanes of saidrot'or, a pair of spaced annular passageways surrounding each cylinder, an auxiliary rotor moving in each one of said passageways delivering air thereto, openings-between each said passageway and its cylinder delivering air under pressure alternately into the exhaust chamber of each cylinder during the power stroke in the other cylinder and into the combustion chamber of each cylinder following the power stroke in that cylinder, an exhaust rotor drivingly connected to the auxiliary rotorin said other passageway, said passageway receiving exhaust gases from the combustion chamber through the driverotorfor' delivery through the exhaust rotorwhereby the auxiliary rotor is driven.

4. An engine of the free piston type comprising a pair of spaced cylinders on acommon axis, a piston movable in each of said'cylinders and connected for u'n'itary 'movement, an expansible combustion chamber on one side of each piston and an expansible exhaust chamber'on the other side of each-pistonja vaned drive rotor adjacent each exhaust chamber, saidrotdrs being connected by a common shaft rotatable around the axis of the cylinders, power transmitting means on said'shaft, means introducing a combustible material alternately into the combustion chamber of each cylinder, a hollow axially extending exhaust tube extending through the pistons and between the cylinders delivering exhaust gas' formed by coinbustion of the combustible'mat'erialfrom' said combustion chamber ofone cylinder to theexha-ust chamber of the other cylinder whereby movement ofthe piston in saidother cylinder 'forces the exhaust gas through thevanes of the rotor, a passageway surroundingeach' cylinder, an auxiliary rotor moving in each said passage delivering air thereto and openings between each said passageway and its cylinder delivering :air under pressure alternately into the exhaust chamber of each cylinder during the power stroke in the other cylinder and into the combustion chamber of each cylinder following the power stroke in that cylinder.

5. An engine of the free piston type comprising a pair of spaced cylinders on a common axis, a piston movable in each of said cylinders and connected for unitary movement, an expansible combustion chamber on one side of each piston and an expansible exhaust chamber on the other side of each piston, a vaned drive rotor adjacent each exhaust chamber, said rotors being connected by a common shaft rotatable around the axis of the cylinders, power transmitting means on said shaft, means introducing a combustible material alternately into the combustion chamber of each cylinder, a hollow axially extending exhaust tube extending through the pistons and between the cylinders, said tube having spaced openings in each cylinder alternately opened and closed by movement of the pistons and carrying exhaust gases from said combustion chamber of one cylinder to the exhaust chamber of the other cylinder whereby movement of the piston in said other cylinder forces the exhaust gas through the vanes of each rotor, a passageway surrounding the cylinder, an auxiliary rotor moving in each said passage and driven by exhaust gases from the vaned rotor delivering air thereto and openings between each said passageway and its cylinder delivering air under pressure alternately into the exhaust chamber of each cylinder during the power stroke in the other cylinder and into the combustion chamber of each cylinder following the power stroke in that cylinder.

6. An engine of the free piston type comprising a pair of spaced cylinders on a common axis, a piston movable n1 each of said cylinders and connected for unitary movement, an expansible combustion chamber on one side of each piston and an expansible exhaust chamber on the other side of each piston, a vaned drive rotor adjacent each exhaust chamber, said rotors being connected by a common shaft rotatable around the axis of the cylinders, power transmitting means on said shaft, means introducing a combustible material alternately into the combustion chamber of each cylinder, a hollow axially extending exhaust tube extending through the pistons and between the cylinders, said tube having spaced openings in each cylinder alternately opened and closed by movement of the pistons and carrying exhaust gases from said combustion chamber of one cylinder to the exhaust chamber of the other cylinder whereby movement of the piston in said other cylinder forces the exhaust gas through the vanes of the rotor, a pair of spaced annular passageways surrounding each cylinder, an auxiliary rotor moving in one of said passageways delivering air thereto, openings between said one passageway and its cylinder delivering air under pressure alternately into the exhaust chamber of each cylinder during the power stroke in the other cylinder and into the combustion chamber of each cylinder following the power stroke in the cylinder, an exhaust rotor drivingly connected to the auxiliary rotor in said other passageway, said passageway receiving exhaust gases from the cylinder through the drive rotor for delivery through the exhaust rotor whereby the auxiliary rotor is driven.

No references cited.

UNITED STATES PATENT OFFICE CERTIFICATION OF CORRECTION Patent No. 2,957,305 October 25, 1960 Andrew I. Sabol It is hereby certified that error appears in the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 3, line 75, after cylinder'fl second occurrence insert ageriod; column 4, lines 1 and 2, strike out "and the rotor and in 0 the cylinder between the cylinder and piston following each exhaust stroke of the piston."; column 5, line 26, for "each rotor a passageway surrounding the" read the rotor, a passageway surroun mg each Signed and sealed this 9th day of May 1961.

(SEAL) Attest:

ERNEST W. SWIDER DAVID L. LADD Attesting Officer Commissioner of Patents 

